As one of the methods for identifying an individual person, there is a method using a fingerprint. In such a method, it is common that an image of a fingerprint is input to an apparatus and the input image is compared with pre-registered fingerprint images. As a method for inputting a fingerprint image, a method in which an inked finger is pressed on a paper surface and a fingerprint is thereby transferred to the paper surface, and then the paper surface, on which the fingerprint is transferred, is read by an image scanner has been used. Further, when a fingerprint having a large range including the sides of the finger is necessary, a fingerprint of the entire finger (rotational fingerprint) is transferred to a paper surface by rotationally moving the inked finger in such a manner that the finger is rolled on the paper surface.
However, in the above-described method, there are problems that a finger is stained with an ink and the method requires a paper. In particular, in the case where a fingerprint is transferred by rotationally moving the finger, unless the finger is rotationally moved on the paper surface in an appropriate manner, the action needs to be repeated again and again. Further, every time the action needs to be repeated, the finger is wiped to remove the adhered ink and a new paper is required. In addition, in the above-described method, every paper on which a fingerprint is transferred needs to be read one by one by using an image scanner in order to convert the image into data, and thus causing a problem that the process is troublesome as a whole.
Accordingly, Patent literatures 1 to 3, for example, proposes a image reading apparatus 80 in which: a finger 83 is placed on a detection surface 82 of a triangular prism (optical prism) 81; the finger 83 is irradiated with light from below by a light source 84; and a rotational fingerprint image is thereby taken by a digital camera 85 equipped with a two-dimensional sensor such as a CCD (solid image-taking device), as shown in FIG. 20.
To obtain the rotational fingerprint image, the digital camera 85 is driven in a successive manner at a frame rate of 30 fps to 60 fps, for example, while a subject person rotationally moves his/her finger 83 on the detection surface 82, so that the entire image of the finger 83 from one side to the other side of the finger is taken as moving images. After that, images of a plurality of frames, which are obtained by the moving-image-taking process, are combined by a synthesis processing unit 86 and a one freeze-frame image is thereby generated. In this way, image data of the rotational fingerprint obtained by converting images from one side to the other side of the finger 83 into one image is obtained.